The present invention relates to pad printers. More particularly, the present invention relates to a roller or roll-on pad printing system.
Pad printing systems are used to apply high quality print, e.g. indicia. Pad printing systems use a deformable pad which receives ink, transferred as an image, from a cliché plate. The plate has an etching or engraving of the indicia formed therein. The image is transferred from the pad to the item into which the indicia is applied.
There are two principal types of pad printers: standard pad printers that use a flat printing plate cast called a cliché, and rotary pad printers that use a drum shaped cliché. In the standard pad printer, a flat cliché plate has the image to be printed etched into the plate. Ink is applied to (and wiped from) the cliché, and the pad is brought into contact with, e.g., pressed into, the cliché until the ink is transferred onto the pad. The pad is then brought into contact with the item to transfer the print onto the item. Both the inking motion (transferring ink from the cliché to the pad) and the printing motion (transferring ink or decoration from the pad to the item) are linear motions.
The rotary pad printer uses a drum-shaped cliché to present ink to a synchronized, counter rotating cylindrical roller pad to transfer ink from the cliché to the pad roll. The roller pad is then moved across the item surface to transfer the ink/decoration to the item.
While both of these methods function very well for printing or decorating certain items or types of items, they do have their drawbacks. For example, traditional (linear motion) pad printing is not effective when printing large areas of ink or when printing images that are very long.
The rotary printer is large and can be costly to manufacture and operate, for example, to manufacture the rotating and counter rotating drum arrangements and the drum-shaped cliché. In addition, rotary printers operate using an ‘open ink well’, which exposes the ink to atmosphere, resulting in more rapid viscosity change due to solvent evaporation, and increased opportunity for ink contamination. Moreover, rotary printers operate on a continuous basis, which is not always a cost effective and efficient manner of operation.
Accordingly, there is a need for a printing system that provides the flexibility of a rotary printer with the ease of use and design of a traditional linear motion pad printer.